[ZODB-Dev] __setstate__ semantics

[Alan Runyan]

I would not imagine this functionality is not in scope of the ZODB. We
were thinking about piggy backing on top of the invalidation messages
sent from ZEO server at one point.. cant remember why we gave up on
it.

For various reasons:

  - The object may not be loaded on the "other" zeo client; therefore
why should it be notified?

  - If you have a lot of changes it could generates oodles of
messages; significantly degrading ZODB performance.

The best thing is to look into a messaging library.  AMQP is pretty
rockin. I spoke w/ Stefan Richter and they are using Amazon's
messaging platform. I believe what you are looking for is some sort of
application level messaging across ZEO clients.

Kapil has started an implementation at repoze.queue (I would prefer
the name repoze.messaging) which may not yet have an implementation
other than the interfaces and some tests.  But this is a known problem
(which is very hard to get right).

cheers
alan

On Mon, Oct 20, 2008 at 2:36 PM, Roché Compaan
<roche at upfrontsystems.co.za> wrote:
> If an object is modified on one ZEO client, will this always lead to a
> __setstate__ call on this object on another ZEO client?
>
> If not, is there any event or method that I can hook into to determine
> if an object was modifed by another ZEO client?
>
> --
> Roché Compaan
> Upfront Systems                   http://www.upfrontsystems.co.za
>
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-- 
Alan Runyan
Enfold Systems, Inc.
http://www.enfoldsystems.com/
phone: +1.713.942.2377x111
fax: +1.832.201.8856